Noise screens, their components and their construction

ABSTRACT

The invention provides sound insulating panels for use in noise screens, the panels being formed from mineral wool of substantially uniform density and average density from about 100 to about 2000 kg/m 3  and thickness not more than about 200 mm. These panels may advantageously be used in noise screens comprising one or two upright support members having I-profile cross-section of width greater than the panel thickness.

FIELD OF THE INVENTION

[0001] This invention relates to screens for reduction of noise and to sound insulating panels for use in forming such screens. Such screens are often used to isolate areas from sources of noise.

BACKGROUND OF THE INVENTION

[0002] Screens of this type are well known. They are generally produced by providing at least one, generally two upright support members or posts. One or more sound insulating panels are positioned between two such upright support members in a vertical plane and are secured in a vertical position by means of these support members. Posts most commonly used as the support members are beams having an I-profile cross-section. These I-profiles are provided in a limited range of dimensions for use in the relevant industry. For instance I-profile support members of height 2 meters tend to have width 160 mm and I-profile support members of height 5 meters generally have width 200 mm.

[0003] Various manufacturers supply the sound insulating panels which are positioned between the support members. There are a wide variety of such panels. They are formed from a variety of different materials, mass and noise insulation and absorption properties of the material being important.

[0004] EP-A-347,966 describes a traffic noise barrier in which the sound insulating panel comprises a slab of mineral wool and a corrugated metal panel. The density of the wool is unspecified.

[0005] EP-A-1,077.446. published Feb. 21, 2001, discloses acoustic barriers formed from panels of sound absorbing material which can be rock wool or glass wool, and again the density of the wool is unspecified.

[0006] WO99/22075 describes a noise screen comprising mineral wool batts and tree stems. The density of the mineral fibre batts used is said to be from 25 to 450 kg/m³, preferably from 40 to 200 kg/m³. The only specific construction described is of several layers of mineral fibre having different density. In particular there is a description and an example of a system having a centre layer having a comparatively low density and two or more encompassing layers with higher density. The average density for the entire layer is from 80 to 150 kg/m³, preferably between 100 and 150 kg/m³. The thickness is described as being generally between 100 and 400 mm. The density expressed as weight per unit area is from 15 to 40 kg/m², preferably 20 to 25 kg/m². In the only example the dual-density system exemplified contains two central layers of wool of density 80 kg/m³ encompassed by two layers of density of about 200 kg/m³. Thickness and weight per unit area are not discussed.

[0007] This latter dual-density construction is in fact the practical embodiment which has been used in commercial practice. It has in the past been assumed that this is the best construction for maximising insulating properties. However, this construction has the disadvantage that in order to optimise insulation properties it has been found necessary to provide the slab at a rather high thickness of 240 mm. This has the problem that the slabs are of greater width than the width of the commonly provided I-profile support members.

[0008] In addition U.S. Pat. No. 5,406,039 discloses acoustical barrier panels comprising concrete, portland cement and chemically mineralised and neutralised fibers, as does U.S. Pat. No. 4,325,457. WO 98/00607 discloses sound absorbing and/or reducing walls which comprise blocks of mineral wool only. This disclosure concerns support means which are not the standard I-profile support members discussed above.

[0009] In systems in which the mineral wool slab has thickness greater than the I-profile width, the sound absorbing panels are generally fixed to the upright I-profile support members by means of a system of Z-profile brackets illustrated in FIG. 1. This figure shows a cross-section through the I-profile (1) and sound insulating panel (2), viewed from above when the system has been constructed.

[0010] The Z-profile brackets (3) are secured to the vertical surfaces of the sound insulating panel and to the outer vertical surfaces of the end pieces (4) of the I-profile support member.

[0011] This system of securement has been used for this type of sound insulating panel for several years. It can lead to difficulties in ensuring securement and necessary materials must be supplied to form the Z-profile. In this particular field cost is a particularly important issue and reducing installation time (and thus cost) and the amount of installation material required is especially important. Nevertheless, this type of sound insulating panel has always been supplied at this single thickness and secured in the same manner.

SUMMARY OF THE INVENTION

[0012] According to a first aspect of the invention we have found that it is possible to provide sound insulating panels, for use in noise screens which are formed from mineral wool, which have a convenient thickness and which nevertheless give excellent insulating properties, by selecting a sound insulating panel formed from mineral wool of uniform density and having a defined average density and a defined thickness.

[0013] According to the invention we provide a sound insulating panel suitable for use as a noise screen wherein the panel is formed from mineral wool having a substantially uniform density, wherein the average density is from about 100 to about 200 kg/m³ and the thickness of the mineral wool is not more than about 200 mm.

[0014] The density of the mineral wool in the panel is substantially uniform. That is, it does not vary across the volume by more than about 10 kg/m³, preferably not more than about 5 kg/m³.

[0015] According to a second aspect of the invention we provide a noise screen comprising

[0016] (a) a first upright support member having an I-profile cross-section of width x₁ and comprising a cross-piece and two end-pieces,

[0017] (b) a sound insulating panel of panel thickness y consisting essentially of MMVF wool and having first and second opposite ends,

[0018] and in which the sound insulating panel is supported by the support member in a substantially vertical position and a first end of the sound insulating panel is positioned between the two end-pieces of the fist I-profile and the panel thickness y is not more than I-profile width x₁.

[0019] In a third aspect the invention provides a noise screen comprising:

[0020] (a) a first upright support member

[0021] (b) a sound insulating panel consisting essentially of MMVF wool

[0022] and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces which are each provided with netting and the netting is secured to the panel by means of a connecting device extending across at least part of the upper substantially horizontal surface of the panel.

[0023] In a fourth aspect of the invention we provide a noise screen comprising:

[0024] (a) a first upright support member

[0025] (b) a sound insulating panel consisting essentially of MMVF wool

[0026] and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces and comprises at least one reinforcing plate within the sound insulating panel in a plane perpendicular to the two substantially vertical side faces.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The panel consists essentially of mineral wool of substantially uniform density. It is possible to include in the panel a very high density mineral wool board forming a small part of the thickness of the panel, in particular less than about 20%, preferably less than about 10%, of the thickness of the panel. Such a board has a density of at least about 600 kg/m³, preferably at least about 700 kg/m³. If such a board is used it can be positioned in the middle of this panel or on one side. However, generally the panel consists only of mineral wool of substantially uniform density.

[0028] We find surprisingly that the choice of uniform density in the range specified, in combination with the defined thickness, gives an optimum combination of absorption and insulation properties. We find that if density if too high then noise absorption is low. However, if the density×thickness value is too low then insulation is low. Thus maintaining a low thickness is difficult if density is too low. We find that the choice of the ranges in the invention optimises both properties.

[0029] Preferably the density×thickness value is at least about 12 kg/m². It is preferably not more than about 25 kg/m², more preferably not more than about 20 kg/m². Values of about 17 kg/m² are particularly valuable.

[0030] The average density is preferably from about 120 to about 180 kg/m³, in particular from about 125 to about 160 kg/m³, and values of about 140 to about 150 kg/m³, in particular about 145 kg/m³ are particularly useful.

[0031] Preferably the panel is formed from two layers of mineral wool wherein each layer has substantially the same average density and each layer has substantially uniform density. Preferably the two layers of mineral wool are of substantially equal thickness.

[0032] The total thickness of the mineral wool is preferably not more than about 190 mm, more preferably not more about 160 mm, and in some cases may be not more than about 150 mm or not more than about 130 mm. Preferably it is at least about 100 mm, more preferably at least about 110 mm.

[0033] According to the invention the sound insulating panel may be used in a noise screen.

[0034] According to a second aspect of the invention we provide a noise screen comprising

[0035] (a) a first upright support member having an I-profile cross-section of width x₁ and comprising a cross-piece and two end-pieces,

[0036] (b) a sound insulating panel of panel thickness y consisting essentially of MMVF wool and having first and second opposite ends,

[0037] and in which the sound insulating panel is supported by the support member in a substantially vertical position and a first end of the sound insulating panel is positioned between the two end-pieces of the first I-profile and the panel thickness y is not more than I-profile width x₁.

[0038] The noise screen comprises at least a first upright support member of I-profile cross-section. Generally it comprises a second upright support member also of I-profile cross-section.

[0039] The upright support members may be made of any suitable material, for instance steel. They may be fixed to the ground or other relevant support surface by known means. In position, they extend substantially vertically and are elongate.

[0040] The sound insulating panel is supported in an upright (substantially vertical) position by means of the support members. The noise screen is generally constructed by placing the support members upright in position and lowering the sound insulating panel into position between the support members. This is common in particular when there are two support members. The sound insulating panel may also be lowered into position when there is only one support member. However, in this latter case it is also possible to transfer the sound insulating panel into position from the side of the support member.

[0041] As can be seen from FIG. 2, a first end (5) of a sound insulating panel (2) is positioned between the two end pieces (4) of the first I-profile (1). This is only possible in the invention because for the first time the panel thickness y is not more than I-profile width x₁. As will be seen from the discussion below, this choice of the relative dimensions, which has not been previously used for sound insulating panels which consist essentially of MMVF wool, allows more rapid and more convenient installation procedures. It also allows the use of less material for securing the sound insulating panel to the support member. As discussed above, any reduction in installation time and installation materials can lead to cost reductions, which are particularly important in this field.

[0042] The sound insulating panel may be according to the first aspect of the invention. However, in the second aspect of the invention this is not essential provided that the panel has a panel thickness y less than I-profile width x₁.

[0043] The sound insulating panel in the second aspect of the invention consists essentially of MMVF wool. Thus, it does not comprise significant amounts of concrete or cement as is U.S. Pat. No. 5,406,039 and U.S. Pat. No. 4,325,457 and does not comprise significant layers formed from non-MMVF materials such as the corrugated panels in EP-A-347966.

[0044] The MMVF wool sound insulating panel may comprise a layer of metal such as aluminium, either in the centre or the panel or on the surface further from the direction from which the sound will come. Generally at least about 80 weight percent, preferably at least about 90 weight percent, more preferably at least about 95 weight percent and often substantially 100 percent of the weight of the sound insulating panel is MMVF wool, supplied if necessary with standard MMVF wool components such as binder and wetting agent.

[0045] Panels for sound insulation which consist essentially of MMVF wool generally act as insulating panels primarily by means of sound absorption. However, some reflection may occur, especially when, as discussed below, the sound insulating panel is also provided with polymeric netting and/or reinforcing netting.

[0046] Generally if binder is present its amount is from about 1 to about 10%, often about 2 to about 5%. Wetting agent is preferably included in the MMVF wool sound insulating panels, in an amount from about 100 to about 1000 ppm, preferably about 200 to about 500 ppm, by weight wetting agent based on weight wool.

[0047] The sound insulating panel consisting essentially of MMVF wool may be formed from a single layer of MMVF wool. Preferably, however, it comprises at least two layers of MMVF wool. In the second aspect of the invention these layers may have the same or different density. Average density is generally from about 60 to about 200 kg/m³, but layers of high density, for instance from about 500 to about 1000 kg/m³, may also be included.

[0048] Preferably the panel consists of two layers of MMVF wool of substantially the same density, as in the first aspect of the invention. Average density is preferably from about 100 to about 200 kg/m³, preferably about 125 to about 160 kg/m³, for instance from 145 kg/m³.

[0049] Preferably the mineral wool has a density (kg/m³)×thickness (m) value of at least about 12 kg/m², more preferably not more than about 25 kg/m², in particular not more than about 20 kg/m², also as in the first aspect of the invention.

[0050] The value of panel thickness y is usually from about 60 to about 200 mm. The panel thickness y is less than the I-profile width x₁ (or x₂ in the case of a second support member). See FIGS. 2 and 3. In this specification the panel thickness y is the thickness of the panel at the end which is positioned between the two end-pieces of the I profile. Generally the thickness of the sound insulating panel is substantially the same along its length. However, it is possible for the panel thickness in the regions which are not between the end pieces of the I-profile to be greater than panel thickness y. In particular, it can be advantageous for the thickness in region A (see FIG. 2) to be substantially the same as the standard width h of the I-profile.

[0051] In the invention the sound insulating panel consists essentially of MMVF wool. Generally it is formed substantially only from one or more slabs of MMVF wool. The panel thickness y is the total thickness of these slabs and any aluminium sheets as discussed above. It does not include the thickness of any light or reinforcing netting (discussed below). If such netting is to be used and is also to be placed between the end pieces of the I profile then the total thickness of the MMVF wool slabs and the netting should be less than the width x₁ of the I-profile.

[0052] The I-profile support members are commercially available products and generally in the invention it is preferred to use such standard products. As supplied, the manufacturer defines the height h of the I-profile, shown in FIGS. 2 and 3. This height h is generally from 120 mm to 240 mm, preferably from 140 to 200 mm. Preferred I-profile support members have height h about 140, about 160, about 180 or about 200 mm.

[0053] It will be seen that this value h is inevitably slightly greater than the I-profile width x₁, which corresponds with the value of h minus the thickness of the two end-pieces. In the invention it is important that the panel thickness y is not more than x₁.

[0054] The I-profile members are generally supplied with a series of standard end-piece lengths b. See FIGS. 2 and 3. The ratio of h to be may be from 0.5:1 to 3:1. Medium breadth I-profiles generally have a ratio of h:b from 1:1 to 3:1, often around 2:1. Broad H-profiles tend to have a ratio of h:b from 0.5:1 to 1.5:1, preferably around 1:1.

[0055] Particularly preferred medium breadth I-profiles have the following combinations of h and b values: h 160 mm, b 82 mm; h 180 mm, b 91 mm; h 200 mm, b 100 mm. Suitable broad I profiles have the following combinations of h and b values: h 133 mm, b 140 mm; h 152 mm, b 160 mm; h 171 mm, b 180 mm; h 190 mm, b 200 mm.

[0056] The preferred means for securing the sound insulating panel to the I-profiles is an L-profile bracket as shown in FIGS. 3, 4 and 5. At least one vertical edge (6) of the sound insulating panel is provided with an L-profile (7) which is usually contiguous with the vertical end face (8) and can be contiguous with the vertical side face (9) (see FIG. 4) of the sound insulating panel which forms the relevant vertical edge. The L profile may be provided on a portion only of the vertical edge but it is preferably provided along substantially the entire length of the vertical edge. Preferably both vertical edges at the first end of the sound insulating panels, more preferably all four vertical edges, are provided with an L profile. The major (i.e. longer) horizontal edges (10) may also be provided with an L-profile, as in FIG. 5.

[0057] As can be seen from FIG. 3, the portion of the L-profile which can be contiguous with the vertical side face is contiguous (on its opposite surface) with and secured to the inner surface (11) of one of the end-pieces (4) of the I-profile. This means of securement results in use of lower amounts of material than the prior art methods shown in FIG. 1.

[0058] Clearly, when L-profiles are used the total of panel thickness y and the thickness of the L-profiles is not more than I-profile width x₁.

[0059] An alternative means of securement is not to provide an L-profile bracket but can be used when the sound insulating panel is provided with reinforcing netting, discussed below.

[0060] Preferred means of securing the L-profile to the end piece of the I-profile support member include self-tapping screws (12) or other known securement means as shown in FIG. 3.

[0061] As can be seen from FIGS. 2, 3 and 6, the sound insulating panel is preferably provided with a light netting (13) on at least the two vertical side faces. It can be provided with such netting on all surfaces. The netting is generally formed from polymeric material such as polyethylene. The light netting has a protective function. The noise screen is often in an outdoor situation and the netting protects the wall from, for instance, birds. The netting is usually elastic and weather resistant.

[0062] The sound insulating panel is also preferably provided with reinforcing netting (14) of greater rigidity. This is generally formed from metal such as steel or aluminium. Electroplated steel can be used. The metal netting may be provided with a protective coating, for instance an anti-corrosion coating, e.g. paint.

[0063] When the noise screen comprises one or more MMVF wool slabs, light netting and reinforcing netting, these may be pre-assembled as a single unit and the noise screen constructed as discussed above. However, it may also be constructed in a stepwise fashion. For instance, the MMVF wool slab may be placed between the two end-pieces of the I-profile, the light netting then positioned and the reinforcing netting subsequently positioned.

[0064] When the vertical side faces of the sound insulating panel are provided with reinforcing metal netting the netting itself may be used as a means of securement. That is, the netting may be secured to an outer surface of an end piece of the I-profile, as shown in FIG. 2. Securement may be directly to the end-piece or by means of a further connecting plate (15). Securement means (12) as discussed above may be used. The use of these systems can increase ease of mounting and requires even less material than the L-profile bracket as discussed above.

[0065] Alternatively the connecting plate (15) may be positioned in contact with the outer surface of the end piece of the I-profile, such that a proportion of its major surface is contiguous with the metal netting and a proportion of the same major surface is contiguous with the outer surface of the end-piece of the I profile. This arrangement is illustrated in FIG. 11.

[0066] When the L-profile bracket system is used and the sound insulating panel is provided with metal netting, the L-profile may be welded to the metal netting. See FIG. 5.

[0067] When an L-profile system is used the method of constructing the sound insulating panel may be as follows.

[0068] When L-profiles are provided on all four major horizontal edges (ie side edges in practice) and all vertical edges, a frame is prefabricated and reinforcing metal netting is welded onto the inner surfaces of the L-profiles. The entire system is electroplated in an electroplating bath. A panel of mineral wool, preferably formed from two layers, having a covering of polyethylene netting, is fitted into the electroplated netting/L-frame system. This prefabricated panel may be transported to the site where the noise screen is to be constructed and positioned between one or more I-profile support members. The system is generally secured with screws.

[0069] If L-profile members are to be used only on the top and bottom major horizontal edges and a flat plate is to be used on the vertical side faces and positioned in connection with the ends of the I-profile end pieces, a similar process can be used.

[0070] An alternative system to use of L-profile members on the major horizontal edges is to provide reinforcing metal netting on the vertical side faces and to bend that netting to cover at least a portion of the horizontal top and bottom surfaces. A flat metal plate may be mounted (preferably welded) on to the outer surface of the metal netting on these top and bottom horizontal surfaces.

[0071] Even when L-profiles are provided on the major horizontal edges a connecting plate, usually metal, may also be provided on either the inner or outer surface of the L-profiles, along part or all of the length of the sound insulating panel.

[0072] When the noise screen is constructed, if the thickness of the sound insulating panel is significantly less than I-profile width x₁, then it is possible to introduce spacing members between the L-profiles and the inner surface of the end pieces of the I-profile, as necessary.

[0073] In practice, when the I-profile width x₁ is around 160 mm, the preferred embodiment is that discussed above in which a single strip is provided such that it contacts the I-profile and the metal reinforcing netting but is not between them. When the I-profile width x₁ is 180 mm or greater the preferred embodiment has an L-profile positioned on each vertical edge of the sound insulating panel.

[0074] Generally it has proved difficult in the past to devise methods of securing reinforcing netting to the sound insulating panel which are convenient and economical. In a preferred aspect of the invention the two substantially vertical side faces are provided with reinforcing netting which is secured to the sound insulating panels by means of a connecting device extending across at least part of the upper substantially horizontal surface of the panel.

[0075] As can be seen in FIGS. 7 and 8, the connecting device (16) is preferably a hollow pipe (17) of inner diameter greater than or equal to the diameter of the substantially vertical netting elements (18) and at least one netting element from each substantially vertical side face is inserted into an end of a hollow pipe in order to secure the netting to the substantially vertical side faces.

[0076] As shown in FIGS. 9 and 10, the connecting device can be a flat, preferably metal, connecting clip (19). The clip has curved ends (20) which hook onto the substantially horizontal netting elements (18).

[0077] This feature may be applied to noise screens which do not incorporate the relationship between panel thickness y and I-profile width x₁.

[0078] Thus in a third aspect of the invention we provide a noise screen comprising:

[0079] (a) a first upright support member

[0080] (b) a sound insulating panel consisting essentially of MMVF wool

[0081] and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces which are each provided with netting and the netting is secured to the panel by means of a connecting device extending across at least part of the upper substantially horizontal surface of the panel.

[0082] Preferred features of the first and second aspects of the invention may be applied to the third aspect of the invention where applicable.

[0083] As shown in FIG. 6, the sound insulating panel may comprise at least one reinforcing plate (19) positioned in a plane perpendicular to the vertical side faces (20). The reinforcing plate may be substantially planar (as shown) or it may be curved. Curvature is generally around an axis parallel to the plane of the reinforcing plate and parallel to the vertical side faces. The plate may alternatively have curvature around one or more axes parallel to the plane of the reinforcing plate and perpendicular to the vertical side faces, for instance the plate may be curved or even waved along the length of the sound insulating panel. Generally the reinforcing plate extends along the entire length of the sound insulating panel (as shown).

[0084] This system is particularly preferred when the length of the sound insulating panel is more than about 3 meters, in particular more than about 3.5 meters and especially when the length is greater than about 4 meters.

[0085] Generally the reinforcing plate is metal but may alternatively be made of a plastic material.

[0086] This system is particularly preferred and can in fact be applied also in noise screens which do not use the ratio between x₁ and panel thickness y discussed above.

[0087] Thus in a fourth aspect of the invention we provide a noise screen comprising

[0088] (a) a first upright support member

[0089] (b) a sound insulating panel consisting essentially of MMVF wool

[0090] and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces and comprises at least one reinforcing plate within the sound insulating panel in a plane perpendicular to the two substantially vertical side faces.

[0091] In this aspect of the invention any of the preferred features of the first to third aspects of the invention may be applied where applicable.

[0092] The MMVF wool may be any suitable man-made vitreous fibre wool, eg. glass wool, slag wool or stone wool. Preferably it is stone wool. It is generally provided in standard manner by centrifugal fiberisation of a melt having the desired composition. Preferably the composition comprises at least 18% alumina.

[0093] Specific embodiments of the invention will now be described with reference to the Figures.

[0094]FIG. 1 shows a top view of the prior art system.

[0095]FIG. 2 shows a top view of one embodiment of the invention.

[0096]FIG. 3 shows a top view of a further embodiment of the invention.

[0097]FIG. 4 shows a top view of an MMVF wool panel for use in the invention.

[0098]FIG. 5 shows a perspective view of L-profiles, connecting devices and reinforcing netting as applied to an MMVF wool panel.

[0099]FIG. 6 shows an exploded view of a sound insulating panel for use in the invention, plus reinforcing netting.

[0100]FIG. 7 shows a perspective view of a connecting device.

[0101]FIG. 8 shows a cross sectional view of the connecting device of FIG. 7.

[0102]FIG. 9 shows a perspective view of a further connecting device.

[0103]FIG. 10 shows a cross section of the connecting device of FIG. 9.

[0104]FIG. 11 shows a perspective view of part of a further embodiment of the invention.

[0105]FIG. 12 shows a perspective view of a further embodiment of the invention.

[0106]FIG. 13 shows a perspective view of a further embodiment of the invention.

[0107]FIG. 1 shows a top view of a prior art system in which the sound insulation panel has a panel thickness greater than the width of the I-profile, As can be seen, it is necessary to use Z-profile brackets 3 in order to mount the sound insulation panel. This is time-consuming, the Z-profile brackets 3 necessarily involve larger amounts of materials than the systems of the invention and it is necessary to be especially precise about positioning the sound insulation panels.

[0108] In these embodiments of the invention the sound insulating panel 2 is formed from two mineral wool slabs each of the same thickness and having density about 145 kg/m².

[0109] In FIG. 2, according to the invention the sound insulating panel 2 has panel thickness y less than the width x₁ of the I-profile. Thus the sound insulation panel can be placed quickly and easily in position between the end pieces 4 of the I-profile.

[0110] In this embodiment the sound insulating panel is formed from a mineral wool slab and is provided with external light poylethylene netting 13 and reinforcing steel netting 14.

[0111] The sound insulating panel is affixed to the I-profile by means of plates 15 contiguous with the outer vertical surface of the end pieces 4 of the I-profile 1. The netting and plates are affixed to the end pieces 4 by means of self tapping screws 12.

[0112] In FIG. 2 the panel thickness y is the same along the length of the sound insulating panel. However, it is possible for only the panel thickness in the region placed between the end pieces of the I-profile to be less than x₁. In the region outside the end of the I-profile (region A) then it may be as much as standard width h of the I-profile or greater.

[0113]FIG. 3 demonstrates a preferred method of affixing the sound insulating panel to the I-profile support member. L-profiles 7 are positioned at each vertical edge 6 of the sound insulating panel. The L-profile is contiguous with vertical end face 8 of the sound insulating panel. Its outer surface is contiguous with inner vertical surface 11 of the end piece of the I-profile. It is affixed to the I-profile by means of self-tapping screws 12.

[0114] In this embodiment, the sound insulating panel is provided with light polyethylene netting 13 and reinforcing netting 14. Both types of netting are positioned inside the L-profile and between the end pieces 4 of the I-profile 1.

[0115] In the invention the sound insulating panel is usually formed from substantially non-compressible MMVF wool. Compressible wool may also be provided between the vertical end face 8 of the sound insulating panel and the cross-piece of the I-profile. This provides additional sound insulation.

[0116]FIG. 4 demonstrates that the L-profile angle may be contiguous with both the vertical side surface 9 and the end surface 8 of the mineral wool slab.

[0117] As shown in FIG. 5, reinforcement may be obtained by providing L-profiles along the upper horizontal edges 10 of the sound insulating panel. These may be welded to the reinforcing netting 14.

[0118]FIG. 6 shows an exploded view of a sound insulating panel for use in the invention. A reinforcing steel plate 10 is positioned in the MMVF wool slab in a plane perpendicular to the substantially vertical side faces. The substantially vertical side faces are provided with light polyethylene netting 13. External reinforcing steel netting 14 is also provided on the substantially vertical side faces.

[0119] The reinforcing netting may be fixed to the substantially vertical side faces by means shown in FIGS. 7, 8, 9 and 10. The connecting device of FIGS. 7 and 8 is a hollow pipe which can be formed of metal. Each end of the pipe has an internal cross sectional which is greater than or equal to the diameter of the netting elements, especially vertical netting elements 18. An end of a netting element is inserted into each end of the hollow pipe.

[0120] In FIGS. 9 and 10 the connecting device is a flat clip often formed of steel or other metal. The ends 20 are curved and hook around horizontal netting elements 18.

[0121] As shown in FIG. 11, a connecting plate is welded to the outer surface of the reinforcing netting 14. A position of this connecting plate 15 is contiguous with the outer surfaces of the end-pieces 4 of the I-profile 1.

[0122]FIG. 12 shows a preferred embodiment in which L-profile angles 7 are positioned on each vertical edge 6 of the sound insulating panel and along the upper horizontal edges 10 of the sound insulating panel. The L-profile angles 7 are welded to the reinforcing netting 14 on its outer surface. In the noise screen itself the vertical L-profile angles are positioned contiguous with the inner surfaces of the end-pieces of the I-profile support member 1.

[0123]FIG. 13 shows a similar embodiment except that no vertical L-profile angles are provided on the vertical edges 6 of the sound insulating panel. Instead a connecting plate 15 is provided. 

1. A sound insulating panel suitable for use in a noise screen, wherein the sound insulating panel is formed from mineral wool having a substantially uniform density, wherein the average density of the mineral wool is from about 100 to about 200 kg/m³ and the thickness of the mineral wool is not more than about 200 mm.
 2. A sound insulating panel according to claim 1 which has a density×thickness value of at least about 12 kg/m².
 3. A sound insulating panel according to claim 2 in which the mineral wool has a density×thickness value of not more than about 25 kg/m², preferably not more than about 20 kg/m².
 4. A sound insulating panel according to claim 1 in which the mineral wool has density about 120 to about 160 kg/m³, preferably from about 140 to about 150 kg/m³.
 5. A sound insulating panel according to claim 1 having a thickness of from about 100 to about 160 mm
 6. A sound insulating panel according to claim 1 formed from two layers of mineral wool, each layer having substantially the same average density and each layer having substantially uniform density.
 7. A sound insulating panel according to claim 6 in which the two layers of mineral wool are of substantially equal thickness.
 8. A noise screen comprising a first upright support member having an I-profile cross-section of width x₁ and comprising a cross-piece and two end-pieces, a sound insulating panel according to claim 1 having panel thickness y and having first and second opposite ends, and which the sound insulating panel is supported by the support member in a substantially vertical position and a first end of the sound insulating panel is positioned between the two end pieces of the I-profile and the panel thickness y is not more than I-profile width x₁.
 9. A noise screen according to claim 8 additionally comprising a second upright support member having a second I-profile cross-section of width x₂ and comprising a cross-piece and two end-pieces and the second end of the sound insulating panel is positioned between the two end-pieces of the second I-profile.
 10. A noise screen comprising (a) a first upright support member having an I-profile cross-section of width x₁ and comprising a cross-piece and two end-pieces, (b) a sound insulating panel of panel thickness y consisting essentially of MMVF wool and having first and second opposite ends, and in which the sound insulating panel is supported by the support member in a substantially vertical position and a first end of the sound insulating panel is positioned between the two end-pieces of the first I-profile and the panel thickness y is not more than I profile width x₁.
 11. A screen according to claim 10 additionally comprising a second upright support member having a second I-profile cross-section of width x₂ and comprising a cross-piece and two end-pieces and the second end of the sound insulating panel is positioned between the two end-pieces of the second I-profile.
 12. A screen according to claim 11 in which the dimensions of the first and second I-profiles are substantially identical.
 13. A screen according to claim 10 in which panel thickness y is from about 60 to about 200 mm.
 14. A screen according to claim 11 in which I-profile widths x₁ and x₂ are the same and are each from about 120 to about 220 mm, preferably from about 150 to about 200 mm.
 15. A screen according to claim 10 in which at least one major horizontal edge of the sound insulating panel is provided with an L-profile contiguous with both the vertical side face and the horizontal top face of the sound insulating panel which form the horizontal edge.
 16. A screen according to claim 15 in which all four major horizontal edges of the sound insulating panel are provided with an L-profile contiguous with the relevant vertical side face and the relevant horizontal top or bottom face.
 17. A screen according to claim 10 in which at least one vertical edge of the sound insulating panel is provided with an L-profile contiguous with both the vertical end face and the vertical side face of the sound insulating panel which form the vertical edge.
 18. A screen according to claim 17 in which all vertical edges of the sound insulating panel are provided with an L-profile contiguous with the relevant vertical end face and the relevant vertical side face.
 19. A screen according to claim 10 in which the vertical side faces of the sound insulating panel are provided with a covering of protective netting, preferably formed from polymeric material, more preferably polyethylene.
 20. A screen according to claim 10 in which both vertical side faces of the sound insulating panel are provided with a covering of metal netting, preferably steel or aluminium netting.
 21. A screen according to claim 20 in which the metal netting is formed from electroplated steel.
 22. A screen according to claim 20 in which at least one major horizontal edge or at least one vertical edge is provided with an L-profile which is formed of metal and is welded to the metal netting.
 23. A screen according to claim 17 in which the portion of the L-profile contiguous with the vertical side face is also contiguous with and secured to the inner surface of an end-piece of the I-profile.
 24. A screen according to claim 22 in which the metal netting is positioned between the L-profile and the MMVF wool.
 25. A screen according to claim 23 in which the L-profile is secured to the end-piece of the I-profile by means of at least one self-tapping screw.
 26. A screen according to claim 10 in which the sound insulating panel has two substantially parallel vertical side faces and comprises at least one reinforcing plate in a plane perpendicular to these vertical side faces.
 27. A screen according to claim 26 in which the reinforcing plate is formed from steel.
 28. A screen according to claim 10 in which the sound insulating panel is impregnated with wetting agent.
 29. A method of constructing a noise screen according to claim 10 comprising providing the first upright support member, providing the sound absorbing panel, and positioning a first end of the panel between the two end-pieces of the first I-profile so that the panel is supported in a vertical position.
 30. A sound insulating panel suitable for use in a noise screen and having panel thickness y of from about 60 to about 200 mm and consisting essentially of a panel of mineral wool which has two substantially parallel vertical side faces and each of these vertical sides faces if provided with a covering of protective netting formed from polymeric material and the surface of the protective netting is provided with a covering of metal netting.
 31. A panel according to claim 30 in which the polymeric material is polyethylene and the metal netting is formed from galvanized steel.
 32. A panel according to claim 30 in which each of the four major horizontal edges is provided with an L-profile contiguous with both the vertical side face and the horizontal top or bottom face of the sound insulating panel which form the relevant horizontal edge.
 33. A panel according to claim 30 in which each vertical edge of the panel is provided with an L-profile contiguous with both the vertical end face and the vertical side face which form the relevant vertical edge.
 34. A panel according to claim 32 in which each L-profile is formed of metal and is welded to the outer surface of the metal netting.
 35. A noise screen comprising (a) a first upright support member (b) a sound insulating panel consisting essentially of MMVF wool and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces and comprises at least one reinforcing plate with the sound insulating panel in a plane perpendicular to the two substantially vertical side faces.
 36. A noise screen comprising (a) a first upright support member (b) a sound insulating panel consisting essentially of MMVF wool and the first upright support member supports the sound insulating panel in a substantially vertical position and the panel has two substantially vertical side faces which are each provided with netting and the netting is secured to the panel by means of a connecting device extending across at least part of the upper substantially horizontal surface of the panel.
 37. A screen according to claim 20 in which the panel is provided with a connecting plate of so that part of the surface of the connecting plate is welded to the outer surface of the metal netting and part of the same surface of the connecting plate is positioned in contact with the outer surface of the end-piece of the I profile. 